On 20 May 2016 at 10:57, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, 20 May 2016, Andy Gross wrote:
>
>> On 20 May 2016 at 09:31, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>> > On Thu, 19 May 2016, Andy Gross wrote:
>> >
>> >> On 19 May 2016 at 05:12, Srinivas Kandagatla
>> >> <srinivas.kandagatla@xxxxxxxxxx> wrote:
>> >>
>> >> <snip>
>> >>
>> >> > +++ b/drivers/usb/host/ehci-hcd.c
>> >> > @@ -368,6 +368,15 @@ static void ehci_shutdown(struct usb_hcd *hcd)
>> >> > {
>> >> > struct ehci_hcd *ehci = hcd_to_ehci(hcd);
>> >> >
>> >> > + /**
>> >> > + * Protect the system from crashing at system shutdown in cases where
>> >> > + * usb host is not added yet from OTG controller driver.
>> >> > + * As ehci_setup() not done yet, so stop accessing registers or
>> >> > + * variables initialized in ehci_setup()
>> >> > + */
>> >> > + if (!ehci->sbrn)
>> >> > + return;
>> >> > +
>> >> > spin_lock_irq(&ehci->lock);
>> >> > ehci->shutdown = true;
>> >> > ehci->rh_state = EHCI_RH_STOPPING;
>> >>
>> >>
>> >> Should we also not check this in ehci_suspend and ehci_resume? If I
>> >> do suspend/resume, it crashes in a similar manner. I know this goes
>> >> beyond the problem scope of the patch. Perhaps I should send in an
>> >> additional patch with the code?
>> >>
>> >> Are there any other places in the ehci-hcd where this needs to be checked?
>> >
>> > Really, this is an indication that the problem lies not in ehci-hcd but
>> > rather in the platform glue code. The platform code allows itself to
>> > be registered as the driver of the controller device but does not
>> > initialize the ehci-hcd parts.
>> >
>> > Neither ehci_suspend nor ehci_resume is called directly by the driver
>> > core; the calls all have to pass through the glue code. So maybe the
>> > glue layer needs to be careful about invoking these routines in
>> > ehci-hcd before ehci-hcd has been initialized.
>>
>> That's a good point. Perhaps all of this should be in the glue,
>> including the shutdown case.
>
> Many of the platform glue files set usb_hcd_platform_shutdown() as
> their shutdown callback, which makes it impossible for them to include
> a controller-specific test.
Yes, I just found this out for myself. So in that specific case, it
makes sense to have the check within the ehci-hcd. Whereas in the
glue driver, the suspend/resume use direct calls to
ehci_suspend/resume.
I'll send along a ehci-msm patch to address the issues i see with
suspend/resume.
Thanks!
Andy
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